Test 1 Ch2 Flashcards by William Djedje

what are six most common elements?

Carbon, hydrogen, nitrogen, oxygen,
phosphorous and sulfur

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structure of an atom

Nucleus: neutrons and protons (positively
charged)
 Cloud of orbiting electrons (negatively
charged)

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what are covalent bonds?

Atoms share electrons in outer most shell to form molecules. All covalent bonds are strong. The strongest bonds.

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what are two types of covalent bonds?

-Non-polar covalent bonds
 Equal attraction or electronegativity for electrons
-Polar covalent bonds
 Unequal attraction for electrons
 Due to difference in electronegativity

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single bonds

2 shared electrons and most free rotation

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double bonds

4 shared electrons

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what are noncovalent bonds?

Non-covalent bonds occur when atoms are
associated, but do not share electrons
Non-covalent bonds are weak, but the sum of non-covalent bonds can be strong

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What are the four noncovalent bonds?

 Ionic bonds
 Hydrogen bonds (very weak)
 Hydrophobic interactions
 Van der Waals forces

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what are ionic bonds?

ionic bonds form between ionized atoms
 Ionization means one atom donates one or more electrons, while the
other atom accepts those electrons
 Cation: atom that donates electron, has positive charge
 Anion: atom that accepts electron, has negative charge

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what is electrostatic attraction?

Opposite charged, inonized atoms are attracted to each other by
electrostatic attraction
Electrostatic attraction is strongest between fully ionized atoms such as Na+
and Cl-. Partially charged atoms are more weakly attracted. Most biological
ionic interactions are between partially charged atoms

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what are hydrogen bonds?

-Interaction between a positively
charged hydrogen ion in one
molecule and negatively charged
atom in another (example of a strong
electrostatic dipole)
-Occurs between highly polar
molecules with hydrogen
- Any molecules with polar covalent
bonds can form H-bonds with water
Individually, very weak bond, 16.7
kJ/mole
- Indicate H bonds with vertical lines

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what are hydrophobic reactions?

-fear of water
Occurs w nonpolar molecules (try to bond with each other to escape water) want to dissociate with water such as fatty acid tails.

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Van Der Waals

Between any two atoms
Consist of dipole-dipole and dispersion forces
As two atoms get closer, fluctuation in electric
charges increase attractions, too close repel
Very weak
Important in protein structure when proteins fit
closely together, sum of all Van der Waals can be
strong

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what is the structure of water?

-water is polar
-forms hydrogen bonds
- has cohesive and adhesive
it effects solubility of other molecules (any molecule charged and polar are hydrophilic)

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Acids

donate protons

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Base

Accepts protons

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pH measures?

concentration (moles/L) of pH-log

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almost all molecules in cells are based on

carbon carbon bonds = organic molecules

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carbon can form covalent bonds with 6 different atoms?

 C-N
 C-O
 C-H
 C-P
 C-C
 C-S

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saturated

Single C-C bond
 Single pair of electrons shared
 Each C bound to three other
atoms –Saturated
 Free rotation

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unsaturated

Double C-C bond
 2 pairs of electrons shared
 Each C bound to two other atoms
– unsaturated
 Fixed – no rotation

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Monosaccharides form

polysaccharides

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fatty acids form

fats and lipids

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amino acids form

proteins and polypeptides

Nucleotides form

nucleic acids

covalent bonds between subunits formed by:

condensation reaction (dehydration synthesis) -molecule of water expelled

Covalent bonds are broken by:

hydrolysis reaction -molecule of water consumed

What do both condensation and hydrolysis reaction requires?

-Enzymes -Condensation reaction always requires energy input

Macromolecules are formed by:

adding subunits to one end of growing polymer in a specific order

Monomer

monosaccharide (simple sugar) -All have formula CH2O..

hydroxyl and carboxyl groups are

polar, thus water soluble

polymer

disaccharide(2) or polysaccharide (many) linked together by glycosidic bonds

Mono and disaccharide (macromolecules) function

immediate energy source for cells

polysaccharide(macromolecules) function

-Starch: energy storage in plants -Glycogen: energy storage in animals (liver and muscle cells) - Cellulose: structural part of cell wall in plants

what is monomers?

a small, basic molecular unit that can bind chemically to other similar molecules to form a larger structure called a polymer. Monomers are the building blocks of polymers, which are complex molecules with repeating structural units.

Lipids (macromolecules)

-Have hydrophilic carboxylic head * Hydrophobic hydrocarbon tail * Saturated, no double bonds * Unsaturated, one or more double bonds * Does not form a true polymer * All lipids/fats are hydrophobic

phospholipid (lipid)

Has two fatty acid tails (one unsaturated) - Have a glycerol group, phosphate group and a hydrophilic head (likes water because polar group + phosphate group) -Big component of cell membrane formed by condensation rxns

Protein (Macromolecule)

-They're long polymers of amino acids linked by peptide bonds know how to draw

Peptide bonds

in proteins, amino acids are joined together by an amide linkage called a peptide bond. -Peptide bonds formed by condensation rxns

R groups

20 total aminos differ by their R groups

Types of R groups:

-Charged (acidic or basic): They can gain or lose e- and their charge is dependent on the pH of the environment -Uncharged, polar: interacts with water - Non-polar: Doesn't interact with water

Covalent bonds between subunits (monomers) form

Macromolecules (polymers) -Noncovalent bonds cause many macromolecules to fold -Noncovalent bonds mediate interactions between molecules

Macromolecules are polymers built from subunits (monomers) covalently inked together by ___________________ reactions.

condensation

Name the specific covalent bond formed between monomers (subunits) of: a. Amino acids: b. Monosaccharaides: c. Nucleotides

a. Peptide bonds b. Glycosidic bonds c. Phosphodiester bonds

Polysaccharide function

energy storage and structural part of cell wall

monosaccharide function

immediate energy source

Nucleic acids function

responsible for storage, transmission, and expression of genetic information

Phospholipids function

major components of cell membranes

Proteins function

catalyze biochemical rxns, provide structural support, regulate cellular processes, transport molecules, facilitate immune responses

draw structure of amino acid pH 7 label alpha carbon, amino group. carboxyl group, r group

draw it

Draw the structural formula of a tripeptide (3 amino acids linked by peptide bonds). Include 3 different R group structures that are likely to found on the outside of a water soluble protein. Label/name each R group. Draw a box around one peptide bond

Draw this

Draw the structural formula of the monosaccharide glucose in the ring structure.

Draw this

Draw the structural formula of a 10 carbon fatty acid with one unsaturated bond. Label the hydrophilic and hydrophobic parts of the fatty acid

draw this

What part of the fatty acid structure makes it an “acid”?

The carboxyl group because it can donate an H+

Draw the general formula of a phospholipid. Include the following labels: fatty acid tails, glycerol group, phosphate group, hydrophilic group.

draw this

Identify each of the molecules below as: monosaccharide, disaccharide, polysaccharide, nucleic acid, nucleotide, amino acid, polypeptide (protein), fatty acid or lipid.

do this on papers

Determine whether the following statement is true or false: In cells, electrostatic attractions are stronger than covalent bonds. This statement is

false

Which of the following covalent bonds is relatively nonpolar? Choose one: A. bond between carbon and hydrogen, –C–H B. bond between nitrogen and hydrogen, –N–H C. bond between oxygen and hydrogen, –O–H

A. -An atom of carbon and an atom of hydrogen attract electrons fairly equally, so the C–H bond is relatively nonpolar. Both oxygen and nitrogen attract electrons more strongly than hydrogen, so these bonds would be polar. Polar chemicals with –OH and/or –NH groups are commonly soluble in water, whereas hydrocarbons of gasoline and oil are not.

What type of bond is formed when one atom donates electrons to another atom?

ionic

Carbon, which has four electrons in its outer shell (with a capacity of eight electrons), can form a maximum of how many covalent bonds with other atoms?

Which type of covalent bond allows for rotation about the bond axis?

single

Regarding acids, bases, and pH, which of these statements is true? Choose one: A. Substances that release protons when they dissolve in water are termed bases and result in a pH lower than 7. B. Substances that release protons when they dissolve in water are termed bases and result in a pH higher than 7. C. Substances that release protons when they dissolve in water are termed acids and result in a pH higher than 7. D. Substances that release protons when they dissolve in water are termed acids and result in a pH lower than 7.

On the basis of weight, which is most abundant in a living bacterial cell? Choose one: A. inorganic ions B. macromolecules C. fatty acids D. proteins E. water

E. water

Which bond term describes a covalent bond in which electrons are shared unequally?

Polar bonds

Which type of bond is the strongest in cells?

covalent

Which term best describes a fatty acid? Choose one: A. amphipathic B. hydrophilic C. hydrophobic D. hydrodynamic

A. amphipathic -Fatty acids contain both hydrophilic (water-loving) and hydrophobic (water-hating) regions, a property that makes them amphipathic and that allows the lipid bilayer to spontaneously form. The interior of the plasma membrane is nonpolar (and thus hydrophobic) and both sides of the plasma membrane are polar (and thus hydrophilic).

What type of bond is formed when two atoms share electrons?

E. covalent bond